Todays motor vehicles have a plurality of electronic systems such as electronic injection and ignition controls and/or ABS-systems. The introduction of further electronic systems has accelerated in order to fulfill even higher future requirements with respect to the environment, use, safety and comfort of motor vehicles. In this context, especially electronic power controls (E-gas), driving-speed control, ASR-systems and/or electronic transmission control systems but also chassis control systems, steering systems including electronic rear-wheel steering, spacing control systems, navigation systems and/or traffic guidance systems have to be mentioned.
In view of the above, the complexity and number of the electronic systems in motor vehicles will increase further. However, in order to provide a satisfactory control of the motor vehicle, an optimal coaction of the individual electronic systems is necessary. This requirement already leads to problems which however will increase in the future. The greatly increasing number of logic connections between the individual systems Causes the complexity of the wiring harness to increase and additional problems occur with respect to the electromagnetic compatibility and the temperature. In addition, space problems become increasingly important with respect to accomodating the individual control devices in the motor vehicles which are designed according to aerodynamic considerations. The developments carried out independently of one another of the individual electronic systems and their necessary logic connection lead to increasing complexity of the development tasks which, in turn, lead to longer development times for the motor vehicle. In addition, disadvantageous effects with respect to reliability, safety and availability of the motor vehicle occur under certain circumstances because of couplings between the individual systems which were not recognized.
The foregoing is opposed by requirements for shorter development time, higher reliability and the requirement that the motor vehicles be easy to maintain. An optimization of the totality of the electronic controls is also required, that is, an optimization of the overall driver-vehicle system with respect to energy consumption, environmental compatibility, power output and comfort, that is an optimization of the operating performance of the motor vehicle for various vehicle models and types.
The procedure to date was on the basis of individual systems logically connected many times with each other and independent of each other. This procedure has reached its limits because of the conflict between the problems described above and the requirements of future control systems. This is especially the case with respect to controlling the overall system. With the structure of the electronic control in a motor vehicle as it has been known to date, the problems described above are neither solved nor are the future requirements satisfied.
For this reason, solutions for electronic overall systems in motor vehicles must be found which fulfill the requirements for shorter development time, higher reliability, availability and reduced service of the motor vehicle while at the same time greatly increasing the use of electronic systems while optimizing the operating performance of the motor vehicle influenced by the totality of the electric systems.
For example, the article of N. A. Schilke et al entitled "Integrated Vehicle Control" published in Convergence 88, pages 97 to 106, discloses a control structure for a motor vehicle having three hierarchial levels without more precise reference to data and command flow and interfaces. The lowest hierarchial level is here defined by the actuator devices carrying out the control functions whereas a second hierarchial level represents the individual control elements of the particular subsystem of the motor vehicle such as brakes, steering, drive, chassis, etcetera. The highest hierarchial level is defined by a coordinator which coordinates the coaction of the individual elements in dependence upon the requests of the driver of the vehicle.
A hierarchial control structure for the coaction of the transmission control and throttle flap control is disclosed in the article of M. Ibamoto et al entitled "Advanced Technology of Transmission Control" published in Hitachi Revue, Volume 39, Number 5, October 1990, pages 307 to 312. The driver request is detected via the following parameters: accelerator pedal angle, engine speed and road speed of the vehicle. Proceeding from the driver request, a desired value for the driving force of the motor vehicle is computed. This desired value is then converted into a corresponding control of the throttle flap and into a gear position.
The above approach considers only a single problem so that the problems with respect to the overall vehicles cannot be solved with these measures.